Centralized Repository
-  Central process acts as control hub 
 
-  Central data repository acts as information hub 
 
-  Termed client-server when based on standalone processes 
 
-  Integrability allows different clients and servers to interoperate 
 
-  Depending on persistency requirements:
	
	-  A blackboard can store temporary data acting as a communications hub 
 
	-  A relational database can provide a persistent data store 
 
	
  
-  In a two-tier architecture the client accesses the database 
 
-  In a three-tier architecture a separate server offers task-oriented services 
 
-  A transaction monitor can be used to offer
	
	-  Resiliency 
 
	-  Redundancy 
 
	-  Load distribution 
 
	-  Message sequencing 
 
	
  
-  Middleware allows different parts to communicate with each other
	
	-  CORBA (OMG) 
 
	-  .NET (Microsoft) 
 
	-  RMI (Java/Sun) 
 
	
  
Examples
-  Window manager 
 
-  File server 
 
-  Print server 
 
-  Collaboration
	
	-  WWW 
 
	-  Modern ERP systems 
 
	-  Instant messaging 
 
	-  Revision control (CVS)